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Bond of reinforcing bars in self-compacting steel fiber reinforced concrete

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Author: Schumacher, P. · Bigaj-van Vliet, A.J. · Braam, C.R. · Walraven, J.C.
Type:article
Date:2002
Institution: TNO Bouw
Source:Festschrift R. Eligehausen, 10
Identifier: 330329
Keywords: Architecture and Building

Abstract

Plain concrete demonstrates a rather brittle behavior both under compression and tension. By adding steel fibers, the post-cracking behavior becomes more ductile and an increase of the strain capacity under tension and compression is found. The research project currently being carried out aims at the development of a model that describes the local bond behavior of deformed bars embedded in a steel fiber reinforced matrix. Considering contradictory conclusions from earlier investigations found in the literature a systematic experimental investigation was carried out. Pull-out tests were carried out on 10 mm diameter deformed reinforcing bars embedded along three times the bar diameter in 200 mm cubes. Plain and steel fiber reinforced concrete (SFRC) with normal strength (B45) were used. The content of fibers was 60 and 120 kg/m3, respectively. While the fiber length was constant (30 mm), the fiber aspect ratio (length/diameter) was varied (45 and 80). Four different concrete covers (15, 25, 35, and 95 mm) were used to investigate both bond failure by splitting of the concrete cover and by shearing off of the concrete corbels between the ribs on the bars. The force-end slip relation was measured and the local bond behavior was analyzed. For a concrete cover of 15 mm, the addition of steel fibers was found to prevent the occurrence of visible splitting cracks, leading to higher bond ductility. The concrete cover thickness of SFRC was found to influence the bond behavior in a similar way as it does for plain concrete.